Dual connectivity refers to the ability of a mobile terminal to communicate simultaneously with two base stations using different carrier frequencies. The advantages of dual connectivity include a reduction in the number of failures in performing handovers of a terminal from one base station to another, a reduction in the amount of signaling required from the network in performing handovers, and enhanced user throughput.
In LTE (Long Term Evolution) cellular systems, as set forth in the specifications of the 3rd Generation Partnership Project (3GPP), a mobile terminal is referred to as user equipment (UE) and a base station is referred to as an evolved Node B (eNB). The UE initially acquires uplink (UL) and downlink (DL) resources from the eNB for transmitting and receiving data by performing a random access (RA) procedure using the physical random access channel (PRACH). The PRACH is a specific set of time-frequency resources allocated by eNB for use by UEs in performing the RA procedure. If periodic scheduling request (SR) resources are not allocated to the UE by the network, the random access process is also used by the UE to acquire uplink resources for all subsequent data transmission. The RA procedure is also used if the UE loses time synchronization with the eNB. The primary concern of the present disclosure is the manner in which random access procedures is performed by a mobile terminal in a dual connectivity context.